Interim Effectiveness Estimates of 2023 Southern Hemisphere Influenza Vaccines in Preventing Influenza-Associated Hospitalizations — REVELAC–i Network, March–July 2023
Authors: Ashley L. Fowlkes, Francisco Nogareda, Annette Regan, Sergio Loayza, Jose Mendez Mancio, Lindsey M. Duca, Paula Couto, Juliana Leite, Angel Rodriguez, Daniel Salas, Eduardo Azziz-Baumgartner, Estefania Benedetti, Andrea Pontoriero, Maria del Valle Juarez, Nathalia Katz, Maria Paz Rojas Mena, Carla Jimena Voto, Walquiria Aparecida Ferreira da Almeida, Daiana Araújo da Silva, Greice Madeleine Ikeda do Carmo, Francisco José de Paula Júnior, Miriam Teresinha Furlam Prando Livorati, Hellen Kássia Rezende Silva, Marcela Avendaño, María Fernanda Olivares Barraza, Patricia Bustos, Paula Rodríguez Ferrari, Natalia Vergara Mallegas, Rodrigo Fasce Pineda, Silvia Battaglia, Marta Von Horoch, Chavely Domínguez, Maria José Ortega, Elena Penayo, Cynthia Vázquez, Hector Chiparelli, Natalia Goñi, Karina Griot, Jose Eduardo Silvera, Daiana Tritten, Steven Tapia Villacís
Journal: MMWR Morbidity and Mortality Weekly Report (2023)

based on data up to 23 July 2023 In this update, in addition to the influenza surveillance information, that of the SARS-CoV-2 surveillance by the Global Influenza Surveillance and Response System (GISRS) through its associated sentinel and non-sentinel surveillance systems and reported to the surveillance data platform FluNet hosted by RespiMART is included.Information on respiratory syncytial virus (RSV) is included where available. Summary▪ Countries are recommended to monitor the relative co-circulation of influenza and SARS-CoV-2 viruses in integrated surveillance and report to RespiMART (FluNet and FluID) directly or via regional platforms.Clinicians should consider influenza in differential diagnosis, especially for high-risk groups for influenza, and test and treat according to national and WHO guidance.▪ Globally, influenza detections remained low, with activity in many countries in the southern hemisphere now decreasing after having peaked in recent weeks.▪ In Oceania, influenza activity decreased, with influenza A viruses predominant.▪ In South Africa, influenza activity of predominately influenza A(H3N2) viruses decreased to below the seasonal threshold after peaking in early June.▪ In temperate South America, influenza detections continued to decrease with A(H1N1)pdm09 viruses most frequently detected followed by B viruses.Severe acute respiratory infections (SARI) activity declined in most countries.▪ In the Caribbean countries, influenza activity remained low overall.▪ In the Central American countries, influenza activity decreased overall with A(H1N1)pdm09 most frequently detected followed by B/Victoria lineage viruses.▪ In the tropical countries of South America, overall influenza activity was low with detections of predominantly A(H1N1)pdm09 and B viruses.▪ In tropical Africa, influenza detections remained low in reporting countries with influenza A(H1N1)pdm09 viruses predominantly detected.▪ In Southern Asia, influenza activity remained low overall except in Bangladesh and the Maldives where detections were elevated.▪ In South-East Asia, influenza activity remained stable in most reporting countries, with continued reporting of predominantly A(H1N1)pdm09 and A(H3N2) virus detections.▪ In the temperate zones of the northern hemisphere, influenza activity was reported at low levels or below seasonal threshold in most reporting countries.Detections were predominantly influenza A(H1N1)pdm09 followed by influenza B and influenza A(H3N2) viruses.▪ Globally, RSV activity was generally low except in some parts of Australia and some countries in tropical and central South America.